Variable orifice die and control therefor

ABSTRACT

Fluid-pressure operable segments surrounding rod-deforming die are controlled by wire-diameter sensing device. As die wear occurs, sensing device responds to increased wire diameter and raises fluid pressure to advance segments inwardly against die thereby to constrict die and decrease diameter of die orifice.

United States Patent [1 1 Fuchs, Jr.

[ VARIABLE ORIFICE DIE AND CONTROL THEREFOR [75] Inventor: Francis Joseph Fuchs, Jr., Princeton Junction, NJ.

Assignee: Western Electric Company,

Incorporated, New York, NY.

Filed:

Division of Ser. No. 122,3]9, March 9, 1971, Fat

[ Jan. 1, 1974 [5 6] References Cited UNITED STATES PATENTS 3,417,589 12/1968 Bobrowsky 72/274 3,564,884 2/1971 Hinshaw 72/57 Primary Examiner-Charles W. Lanham Assistant ExaminerRobert M. Rogers AtlOrneyW. M. Kain et al.

[57] ABSTRACT Fluid-pressure operable segments surrounding rod- ,065. deforming die are controlled by wire-diameter sensing device. As die wear occurs, sensing device responds to Cl 72/274 increased wire diameter and raises fluid pressure to Int. Cl B2") 37/00 advanc egments inwardly against die thereby to con- Field of Search 8. strict die and decrease diameter of die orifice.

17 Claims, 4 Drawing Figures j 4 G v /2-- 56 3 w K 7 A s .12. 123i. l w V ,x 35 Z Z0 22 4o 23 1 7 This is a division, of application Ser. No. 122,319 filed Mar. 9, 1971, now U.S. Pat. No. 3,719,065.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to the deformation of rod in a die to form a wire product. More specifically, this invention relates to deformation, by drawing or extrusion, of rod in a fluid-pressure controlled variable orifice die, with sensing meansmonitoring the diameter of the wire product and increasing the fluid pressure controlling the variable orifice die to constrict the die orifice to compensate for die wear.

2. Description of the Prior Art In a conventional wire drawing operation, rod is pulled through a series of draw dies and is thereby successively reduced in diameter until the desired wire size is obtained.

Conventionally, the draw dies are provided with annular diamond inserts which engage the rod and reduce the diameter thereof. Notwithstanding the inherent hard-ness of diamond, the wear of the diamond dies is so great that the diamond inserts may require replace ment as often as every eight hours, in order to maintain the diameters of the orifices of the die inserts within tolerable limits.

It will be understood that variation in die orifice di ameter produces corresponding variation in the diameter of the wire product, which latter causes numerous problems. Thus, whenever the die orifice diameter is larger than necessary or desired, an excess of rod material passes through the die causing material waste and economic loss. Moreover, electrical characteristics of nonuniform diameter wire will vary from those desired.

Although the foregoing discussion was specifically directed to wire drawing operations, similar problems caused by oversized dies also arise in wire extrusion operations.

SUMMARY OF THE INVENTION diameter of the orifice of a rod deforming die in re sponse to increase in the diameter of the wire product caused by die wear.

Other and further objects of this invention will become apparent during the course of the following description and by reference to the accompanying drawings and to the appended claims.

Briefly, I have discovered that the foregoing objects may be attained by providing a fluid-pressure controlled variable orifice die through which the rod may be passed, as by drawing or extrusion, to form a wire product, and by providing a sensing device which monitors the diameter of the wire product and increases the fluid pressure controlling the variable orifice die thereby to constrict the die orifice to compensate for die wear.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings, in which like numerals represent like parts in the several views:

FIG. 1 represents a view showing the rod passing through the die of the present invention, the die being shown in medial longitudinal section, the sensing device monitoring the diameter of the wire product and the transducer operatively interposed between the sensing device and the die being indicated diagrammatically;

FIG. 2 represents a sectional view of the die taken along the line 2-2 of FIG. 1;

FIG. 3 represents a sectional view of the die, similar to FIG. 2, and shows a modification of the sensing device; and

FIG. 4 represents a vertical view of the die, generally similar to FIG. 3, and shows a further modification of the sensing device.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the embodiment of FIGS. 1 and 2, fluid-pressure controlled variable orifice die assembly 1 is shown as deforming rod 2 to produce wire product 3. Sensing device 4 continuously monitors the diameter of the wire product 3 and produces a signal in response thereto, the said signal controlling, through transducer 5, the fluid pressure in die assembly 1, and thereby controlling the diameter of the orifice of the said die assembly 1.

Die assembly 1 is seen as comprising circular housing 6 having a threaded male portion 7 adapted to be screwed into threaded female portion 8 of circular cap 9. Housing 6 has a central opening 10 extending therethrough and adapted to receive rod 2. An annular recess 11 is formed in the interior face of housing 6, providing a tapered seat 12 and a shoulder 13.

Cap 9 has a central opening 14 extending therethrough and adapted to receive wire product 3. An annular recess 15 is formed in the interior face of cap 9, providing a tapered seat 16 and a shoulder 17.

When housing 6 and cap 9 are assembled as shown in FIG. 1, with their respective annular recesses 11 and 15 facing each other, a chamber 18 is defined. Within chamber 18 are disposed a plurality of wedge-shaped segments 19 surrounding a die 20, the said die 20 being positioned in the space between shoulders 13 and 17 of housing 6 and cap 9, respectively.

Die 20 has a circular outer periphery 21, and the innermost portions 22 of segments 19 are concave arcs of a circle of the same diameter as the outer periphery 21 of die 20, whereby the segments 19 are adapted to properly seat on their respective portions of the outer periphery 21 of die 20. It will be noted that the outer periphery 21 extends beyond the tapered seats 12 and 16 of housing 6 and cap 9. In other words, the diameter of outer periphery 21 of die 20 is somewhat greater than the diameter of tapered seats 12 and 16, measured at shoulders 13 and 17, respectively.

The outer periphery 23 of segments 19, in assembled relation, is circular. Mounted within chamber 18 in engagement with the entire outer periphery 23 of segments 19, is a liner or band 24 which is adapted to be forced, by means hereinafter to be described, inwardly against the outer periphery 23 of segments 19 whereby to constrict the said segments 19. Liner or band 24 is,

in effect, the movable wall of a fluid expandable chamber 25 within chamber 18. Liner 24 is preferably constructed of metallic material, such as a berylliumcopper alloy, or other alloy having a relatively low modulus of elasticity. Alternatively, liner 24 may be constructed of resilient non-metallic material.

Housing 6 is provided with opening 26 communicating with chamber 25 and having a threaded inlet adapted to receive the threaded end of a fluid conduit 27.

It will be noted that, initially and with nominal fluid pressure in chamber 25, when segments 19 are assembled around die 20, there is a small uniform clearance 28 between adjacent segments 19. It will be recalled that, in such initial condition, the outer periphery 21 of die 20 extends beyond the minimum diameter of the tapered seats 12 and 16, and thus there is some clearance between the tapered portions 29 of segment 19 and the said tapered seats 12 and 16.

Thus, when fluid pressure is increased within chamber 25, through conduit 27, liner 24 is forced inwardly against the outer periphery 23 of segments 19, thereby constricting the said assembly of segments 19 about die 20, and thereby constricting the said die 20 and decreasing the diameter of the orifice 30 through the said die 20.

It will be noted that, inasmuch as the area of segments 19 to which fluid pressure is applied, through liner 24, is much greater than the area of segments 19 bearing on die 20, a force amplification effect is achieved, enabling considerable pressures to be exerted on die 20 by means oflower fluid pressure on segments 19 through the said liner 24.

Sensing device 4 may be any one of several wire diameter monitoring devices known in the art. For example, sensing device 4 may employ the techniques of wire diameter measurement utilizing the generation and detection of light diffraction patterns as disclosed in that portion entitled Wire Diameter Monitoring Systems," and specifically that sub-portion entitled "Simple Diffraction Effects," ofa paper, Lasers in lndustry," by R. M. Lumley et al. delivered before U. S. Health Service personnel at Rutgers University on Oct. 2l, 1968. Sensing device 4, which is positioned on the exit side of die assembly 1, continuously measures the diameter of wire product 3 and continuously generates an electrical signal which is a function of the diameter of the said wire product 3.

The electrical signal from sensing device 4 is fed, through line 31 shown schematically in FIG. 1, to transducer 5.

Transducer may be any one of several types known in the art for converting an electrical signal to a fluid pressure signal. Specifically, when the electrical signal from sensing device 4 indicates that the diameter of wire product 3 has increased beyond a predetermined limit, indicating that excessive wear has occurred in die 20, transducer 5, in response to such electrical signal, will produce a higher pressure fluid signal in conduit 27, thereby to increase the fluid pressure in chamber The operation of the embodiment of FIGS. 1 and 2 should be apparent. in summary, sensing device 4 continuously monitors the diameter of wire product 3 drawn or extruded through die and, when die wear occurs such as to produce wire 3 having greater than a predetermined maximum diameter, the electrical signal from sensing device 4 operates, through transducer 5, to increase the fluid pressure in chamber 25 to constrict segments 19 and decrease the diameter of the orifice of die 20, thereby to compensate for die wear and bring the diameter of the wire product 3 below the predetermined upper limit.

A particular advantage of the present invention permits the use of dies 20 which are less expensive than diamond dies. Such dies 20 may, for example, be made of carbide steel. Although such less-expensive dies do not exhibit the same resistance to wear as diamond dies, the die orifice diameter control means of the present invention may provide such less-expensive die with greater effective and useful life than a diamond die without the die orifice diameter control of the present invention.

in that embodiment of the invention shown in FIG. 3, cap 9 is provided with flange 31. Housing 32 with flange 33 is mounted adjacent to die housing 1, suitable threaded bolts (not shown) being passed through apertures in flanges 31 and 33 and threadably receiving nuts (not shown), whereby the said flanges 31 and 33, and thereby the said die housing 1 and housing 32 are secured together.

Housing 32 is provided with a chamber 34 communicating with conduit 35, the latter surrounding and receiving wire 3 and being dimensioned as hereinafter described.

Opening 36, with threaded inlet adapted to receive the threaded end of a fluid conduit 37, communicates between chamber 34 and conduit 27.

In the preferred embodiment, pump 38, with suction connection to a suitable source (not shown) of fluid, has its discharge connected through adjustable flow control valve 39 to conduit 27. Valve 39 can be adjusted to deliver a constant volumetric rate of fluid. Alternatively, pump 38 can be of the constant volume type, in which event valve 39 need not be employed.

Seal 40 is interposed between housing 32 and die housing 1 to prevent leakage of fluid from chamber 34 between the said housing 32 and die housing 1.

The diameter of conduit 35 preferably is chosen to be slightly in excess of the maximum acceptable diameter of wire 3.

It will be apparent that, with fluid pressure in chamber 34, and with the diameter of wire 3 lying within acceptable limits (i.e., wire 3 has a diameter no larger than the accepted value) so that there will be some clearance between wire 3 and conduit 35, there will be some leakage of fluid from chamber 34 through conduit 35 to the atmosphere. The rate of fluid leakage will be a function of the pressure drop from end-to-end of conduit 35 (i.e., the pressure in chamber 34), the length of conduit 35, the clearance between conduit 35 and wire 3, the viscosity of the fluid, and the velocity of the wire. With all these factors constant, the rate of leakage will likewise be constant. It will also be apparent that such fluid leakage through conduit 35 constitutes the bleeding off of fluid from conduit 27.

In operation, initially, valve 39 is adjusted to a threshold value, so that fluid leaks through conduit 35 at a constant rate and the pressure in chamber 35 is just sufficient to urge segments 19 against die 20 but without sufficient force to constrict the said die 20. As die wears occurs, during the course of operation, the diameter of wire 3 increases, the clearange between conduit 35 and wire 3 decreases, less fluid is bled off from conduit 27, and the pressure in chamber 25 increases. Through the hereinbefore mentioned force amplification effect, segment 19 will be urged inwardly with sufficient force to constrict die 20 thereby to retard the adverse effect of die wear on wire diameter.

In the event the force amplification effect is insufficient to adequately constrict die 20, the embodiment of FIG. 4 is employed, which embodiment is generally similar to that of FIG. 3, except that a conventional fluid pressure booster or amplifier 41 is employed. Conduit 27 communicates between the output of fluid pressure booster 41 and chamber of die housing 1 through opening 26. Pump 38 operating through flow control valve 39 pressurizes conduit 42 communicating with the input of fluid pressure booster 41, conduit 37 bleeding off fluid from conduit 42 through conduit 35 as hereinbefore described in connection with the operation of the embodiment of FIG. 3.

The operation of the embodiment of FIG. 4 will be apparent, being identical to that of FIG. 3, except that the pressure level in chamber 25 is amplified through fluid pressure booster 41 sufficiently to force segments 19 against die 20 thereby to adequately constrict orifice and thereby retard the adverse effect of die wear on wire diameter.

I claim:

1. Apparatus for deforming rod to produce wire, said apparatus comprising:

a. a die having an orifice therethrough adapted to receive and deform rod to produce wire, said die being subject to wear whereby said orifice increases in transverse dimension in use;

b. a plurality of members disposed around the outer periphery of said die;

c. fluid-pressure operated motive means operatively associated with said members and adapted to force said members inwardly against the outer periphery of said die thereby to constrict said orifice;

(1. control means adapted to monitor a transverse dimension of said wire to detect increase thereof, said control means being further adapted to adjust the fluid pressure operating said motive means in response to increase in transverse dimension of said wire thereby to constrict the said orifice in response to die wear;

said control means comprising:

e. a first conduit connected to said fluid-pressure operated motive means;

f. pump means to deliver fluid to said first conduit;

g. a second conduit adapted to surround a portion of the length of said wire, and defining with said wire an annular fluid passage;

h. a third conduit communicating between said first conduit and said annular fluid passage and adapted to continually bleed off from said first conduit to said annular fluid passage fluid delivered to said first conduit.

2. Apparatus as in claim 1, wherein said pump means is adapted to deliver fluid to said first conduit at a constant rate.

3. Apparatus as in claim 2, wherein said pump means comprises:

a constant volume pump.

4. Apparatus as in claim 2, wherein said pump means comprises: 2

a pump,

a flow control valve operatively interposed between the discharge of said pump and said first conduit.

5. Apparatus as in claim 2, further comprising:

fluid pressure amplifying means operatively associated with said first conduit and adapted to amplify fluid pressure in said motive means.

6. Apparatus for deforming rod to produce wire, said apparatus comprising:

a. a die having a circular orifice therethrough adapted to receive and deform rod to produce wire, said die having a circular outer periphery and being subject to wear whereby said orifice increases in diameter in use;

b. an assembly of a plurality of tapered segments arranged around the circular periphery of said die, the outer periphery of said assembly being circular, adjacent segments of the assembly being spaced from each other;

c. fluid-pressure operated motive means operatively associated with the circular periphery of said assembly and adapted to force said segments uniformly inwardly against the circular outer periphery of said die thereby to constrict said orifice;

d. control means adapted to monitor the diameterof said wire to detect increase thereof, said control means being further adapted to adjust the fluid pressure operating said motive means in response to increase in diameter of said wire thereby to constrict the said orifice in response to die wear;

said control means comprising:

e. a first conduit connected to said fluid-pressure operated motive means;

f. pump means to deliver fluid to said first conduit;

g. a second conduit adapted to surround a portion of the length of said wire and defining with said wire ari annular fluid passage;

h. a third'conduit communicating between said first conduit and said annular fluid passage and adapted to continually bleed off from said first conduit to said annular fluid passage fluid delivered to said first conduit.

7. Apparatus as in claim 6, wherein said pump means is adapted to deliver fluid to said first conduit at a constant rate.

8. Apparatus as in claim 7, wherein said pump means comprises:

a constant volume pump.

9. Apparatus as in claim 7, wherein said pump means comprises:

a P p a flow control valve operatively interposed between the discharge of said pump and said first conduit.

10. Apparatus as in claim 7, further comprising:

fluid pressure amplifying means operatively associated with said first conduit and adapted to amplify fluid pressure in said motive means.

11. Apparatus for deforming rod to produce wire,

said apparatus comprising:

a. a housing having a central opening formed therethrough along its longitudinal axis;

b. a transverse slot formed in the central portion of said housing and communicating with said central opening;

c. a die having an orifice therethrough, said die being mounted within said housing in said slot, said orifice registering with said central opening, said die being adapted to receive and deform rod to produce wire, said die having a circular outer periphery, said die further being subject to wear whereby said orifice increases in diameter in use;

d. an annular chamber formed within said housing, the outer periphery of said die extending into said chamber;

e. an assembly of a plurality of tapered segments disposed in said chamber, the inner portions of said segments being formed with a curvature corresponding to the curvature of the circular outer periphery of the die, the inner portions of said segments engaging the circular outer periphery of said die, the outer periphery of said assembly of segments being circular, adjacent segments of said assembly being spaced from each other;

. a band disposed within said chamber and inwardly spaced from the outer wall of said chamber, said band constituting a movable wall of an expandable sub-chamber within the said chamber, said band engaging the circular outer periphery of said assembly of said segments;

g. control means adapted to monitor the diameter of said wire and to detect increase thereof, said control means introducing fluid pressure within said expandable sub-chamber in response to increase in diameter of said wire to force said band against the circular outer periphery of said assembly of segments thereby to force said segments uniformly inwardly against the circular outer periphery of said die whereby to constrict said orifice;

said control means comprising:

h. a first conduit connected to said expandable subchamber;

i. pump means to deliver fluid to said first conduit;

j. a second conduit adapted to surround a portion of the length of said wire and defining with said wire an annular fluid passage;

k. a third conduit communicating between said first conduit and said annular fluid passage and adapted to continually bleed off from said first conduit to said annular fluid passage fluid delivered to said first conduit.

12. Apparatus as in claim 11, wherein said pump means is adapted to deliver fluid to said first conduit at a constant rate.

13. Apparatus as in 'claim 12, wherein said pump means comprises:

21 constant volume 14. Apparatus as in claim l2,.wherein said pump means comprises:

a pump,

a flow control valve operatively interposed between the discharge of said pump and said first conduit.

15. Apparatus as in claim 12, further comprising:

fluid pressure amplifying means operatively associated with said first conduit and adapted to amplify fluid pressure in said expandable subchamber.

16. Method for deforming rod, in a die subject to wear, said method comprising:

a. passing said rod through the circular orifice of a die to deform said rod and produce wire;

b. simultaneously with step (a), subjecting the outer periphery of said die to force determined by the pressure of a body of fluid while continually bleeding off fluid from said body of fluid at a rate which is an inverse function of the diameter of said wire;

c. whereby increase in diameter of said wire will produce an increase in the pressure of the body of fluid and hence an increase in the force applied to the outer periphery of said die thereby to constrict said orifice in response to die wear.

17. Method for deforming rod, in a die having a circular outer periphery and subject to wear, said method comprising:

a. passing said rod through the circular orifice of a die to deform said rod and produce wire;

b. simultaneously with step (a);

i. supplying fluid at a constant volumetric rate to a confined body of fluid, whereby to establish a pressurized body of fluid,

ii. applying force determined by the pressure of said body of fluid to the circular outer periphery of said die,

iii. continually bleeding off fluid from said body of fluid at a rate which is controlled by the diameter of said wire, said rate being an inverse function of the diameter of said wire,

0. whereby increase in diameter of said wire will produce an increase in the pressure of the body of fluid and hence an increase in the force applied to the circular outer periphery of said die thereby to constrict said orifice in response to die wear.

L -566- PT UNITED STATES PATENT 0FFICE CERTIFKIATE ()F CORRECTION PatenrNo. 3782l5u Dated January memo) FRANCIS JOSEPH FUCHS, JR.

It is certified that error appears in the above-identified parenr and that said Letters Patent are hereby corrected as shown below:

In the Title page, column 2, "Attorney W. M. Kain et a1." 1 should read --Attorney Jack: Schuman--. (Only.

IN THE SPECIFICATION: Column 1, line 27, "hard-ness' should read --hardness--. Column L, line 65, "wears should read --wear--; line 66, "clearange" should read -clearance--.

IN THE CLAIMS: Column 5, claim 3, line 63, insert --(i)-- before "a constant"; claim L, line 66, insert' ---i)-- before "a pump"; line 67, insert --(j)-- before "a flow Column 6, claim 5, line 3, insert --(i)-- before "fluid"; Claim 8,

line #6, insert --(i)-- before "a constant"; claim 9, line M9, insert --(i)v before "a pump; line 50, insert before "a flow"; claim 10, line 53, insert i before 'fluid" Column 7, claim 13, line LT, insert .1 before "a constant" Column 8, claim 1 L, line 3, insert ---(l)--'- before "a pump,"; line L, insert --(m)-- before "a flow 5 claim 15, line 7, insert --(l)-' before 'fluid" Signed and sealed this 23rd day of Apr 11 19714..

EAL) Attest:

EDWARD M .FLET CHER J R MARSHALL DANN Attesting; Officer 1 Commissioner of Patents 

1. Apparatus for deforming rod to produce wire, said apparatus comprising: a. a die having an orifice therethrough adapted to receive and deform rod to produce wire, said die being subject to wear whereby said orifice increases in transverse dimension in use; b. a plurality of members disposed around the outer periphery of said die; c. fluid-pressure operated motive means operatively associated with said members and adapted to force said members inwardly against the outer periphery of said die thereby to constrict said orifice; d. control means adapted to monitor a transverse dimension of said wire to detect increase thereof, said control means being further adapted to adjust the fluid pressure operating said motive means in response to increase in transverse dimension of said wire thereby to constrict the said orifice in response to die wear; said control means comprising: e. a first conduit connected to said fluid-pressure operated motive means; f. pump means to deliver fluid to said first conduit; g. a second conduit adapted to surround a portion of the length of said wire, and defining with said wire an annular fluid passage; h. a third conduit communicating between said first conduit and said annular fluid passage and adapted to continually bleed off from said first conduit to said annular fluid passage fluid delivered to said first conduit.
 2. Apparatus as in claim 1, wherein said pump means is adapted to deliver fluid to said first conduit at a constant rate.
 3. Apparatus as in claim 2, wherein said pump means comprises: a constant volume pump.
 4. Apparatus as in claim 2, wherein said pump means comprises: a pump, a flow control valve operatively interposed between the discharge of said pump and said first conduit.
 5. Apparatus as in claim 2, further comprising: fluid pressure amplifying means operatively associated with said first conduit and adapted to amplify fluid pressure in said motive means.
 6. Apparatus for deforming rod to produce wire, said apparatus comprising: a. a die having a circular orifice therethrough adapted to receive and deform rod to produce wire, said die having a circular outer periphery and being subject to wear whereby said orifice increases in diameter in use; b. an assembly of a plurality of tapered segments arranged around the circular periphery of said die, the outer periphery of said assembly being circular, adjacent segments of the assembly being spaced from each other; c. fluid-pressure operated motive means operatively associated with the circular periphery of said assembly and adapted to force said segments uniformly inwardly against the circular outer periphery of said die thereby to constrict said orifice; d. control means adapted to monitor the diameter of said wire to detect increase thereof, said control means being further adapted to adjust the fluid pressure operating said motive means in response to increase in diameter of said wire thereby to constrict the said orifice in response to die wear; said control means comprising: e. a first conduit connected to said fluid-pressure operated motive means; f. pump means to deliver fluid to said first conduit; g. a second conduit adapted to surround a portion of the length of said wire and defining with said wire an annular fluid passage; h. a third conduit communicating between said first conduit and said annular fluid passage and adapted to continually bleed off from said first conduit to said annular fluid passage fluid delivered to said first conduit.
 7. Apparatus as in claim 6, wherein said pump means is adapted to deliver fluid to said first conduit at a constant rate.
 8. Apparatus as in claim 7, wherein said pump means comprises: a constant volume pump.
 9. Apparatus as in claim 7, wherein said pump means comprises: a pump, a flow control valve operatively interposed between the discharge of said pump and said first conduit.
 10. Apparatus as in claim 7, further comprising: fluid pressure amplifying means operatively associated with said first conduit and adapted to amplify fluid pressure in said motive means.
 11. Apparatus for deforming rod to produce wire, said apparatus comprising: a. a housing having a central opening formed therethrough along its longitudinal axis; b. a transverse slot formed in the central portion of said housing and communicating with said central opening; c. a die having an orifice therethrough, said die being mounted within said housing in said slot, said orifice registering with said central opening, said die being adapted to receive and deform rod to produce wire, said die having a circular outer periphery, said die further being subject to wear whereby said orifice increases in diameter in use; d. an annular chamber formed within said housing, the outer periphery of said die extending into said chamber; e. an assembly of a plUrality of tapered segments disposed in said chamber, the inner portions of said segments being formed with a curvature corresponding to the curvature of the circular outer periphery of the die, the inner portions of said segments engaging the circular outer periphery of said die, the outer periphery of said assembly of segments being circular, adjacent segments of said assembly being spaced from each other; f. a band disposed within said chamber and inwardly spaced from the outer wall of said chamber, said band constituting a movable wall of an expandable sub-chamber within the said chamber, said band engaging the circular outer periphery of said assembly of segments; g. control means adapted to monitor the diameter of said wire and to detect increase thereof, said control means introducing fluid pressure within said expandable sub-chamber in response to increase in diameter of said wire to force said band against the circular outer periphery of said assembly of segments thereby to force said segments uniformly inwardly against the circular outer periphery of said die whereby to constrict said orifice; said control means comprising: h. a first conduit connected to said expandable subchamber; i. pump means to deliver fluid to said first conduit; j. a second conduit adapted to surround a portion of the length of said wire and defining with said wire an annular fluid passage; k. a third conduit communicating between said first conduit and said annular fluid passage and adapted to continually bleed off from said first conduit to said annular fluid passage fluid delivered to said first conduit.
 12. Apparatus as in claim 11, wherein said pump means is adapted to deliver fluid to said first conduit at a constant rate.
 13. Apparatus as in claim 12, wherein said pump means comprises: a constant volume pump.
 14. Apparatus as in claim 12, wherein said pump means comprises: a pump, a flow control valve operatively interposed between the discharge of said pump and said first conduit.
 15. Apparatus as in claim 12, further comprising: fluid pressure amplifying means operatively associated with said first conduit and adapted to amplify fluid pressure in said expandable sub-chamber.
 16. Method for deforming rod, in a die subject to wear, said method comprising: a. passing said rod through the circular orifice of a die to deform said rod and produce wire; b. simultaneously with step (a), subjecting the outer periphery of said die to force determined by the pressure of a body of fluid while continually bleeding off fluid from said body of fluid at a rate which is an inverse function of the diameter of said wire; c. whereby increase in diameter of said wire will produce an increase in the pressure of the body of fluid and hence an increase in the force applied to the outer periphery of said die thereby to constrict said orifice in response to die wear.
 17. Method for deforming rod, in a die having a circular outer periphery and subject to wear, said method comprising: a. passing said rod through the circular orifice of a die to deform said rod and produce wire; b. simultaneously with step (a); i. supplying fluid at a constant volumetric rate to a confined body of fluid, whereby to establish a pressurized body of fluid, ii. applying force determined by the pressure of said body of fluid to the circular outer periphery of said die, iii. continually bleeding off fluid from said body of fluid at a rate which is controlled by the diameter of said wire, said rate being an inverse function of the diameter of said wire, c. whereby increase in diameter of said wire will produce an increase in the pressure of the body of fluid and hence an increase in the force applied to the circular outer periphery of said die thereby to constrict said orifice in response to die wear. 